Unity WebGL Build on BrightSign Player stuck loading - unity3d

Question

I want to run a Unity WebGL build on a BrightSign XT1144 player. (What should be possible in theory...)
Therefore I created an absolute simplistic Unity project (using v2020.2.6f1), not much more than displaying an image, and build it for WebGL. Then I published this build to the player using BrightAuthor:connected (using a HTML 5 Widget).
When I start the player the typical Unity WebGL loading screen appears and stops at approx. 90%.
Right now the build works fine on a local server and also online, but not on the BrightSign player.
I played around with the build/player settings in Unity but the behaviour of the build didn't change. (And of course I googled my fingertips bloody, but it's hard to find any kind of valid information...)
Does anyone already have experience with a scenario like this? Any help would be appreciated! :)
Things I tried:
Enabled Development Build
Disabled Compression
Disabled Data Caching
Disabled Engine Code Stripping
Updated BrightSign OS to 8.2.72

Answer 1

Finally I got it working!
This post in the Unity forum got me on the right track.
With the following publishing settings, my Unity (2020.3.2) WebGL build runs on the BrightSign XT1144 player. (BrightSignOS 8.x)

Answer 2

For anyone else that stumbles across this, got close with asj's solution but, at least when building with Unity 2021.3.1f1 and running on a Brightsign XD1033 on OS 8.4.14, I was getting the error
It seems your browser does not support running Unity WebGL content from file:// urls. Please upload it to an http server, or try a different browser.
Looks like Unity WebGL projects won't run locally anymore. Followed Brightsign's instructions here to get started with a NodeJS server on the Brightsign to host the WebGL. Moved everything created by the Unity build (index.html, Build, TemplateData, StreamingAssets) to a client folder within the node.js-starter-project-master folder. Modified the index.js express script to
const path = require('path');
var app = express();
app.use(express.static(path.join(__dirname, '/storage/sd')));
app.use(express.static(path.join(__dirname,'./client')));
app.get('/*', function (req, res) {
res.sendFile(path.join(__dirname, './client/index.html'));
});
app.listen(9090, function() {
console.log('Example app listening on port 9090!');
});
Also had to update webpack.config.js so the client directory was copied to dist. Replaced the CopyWebpackPlugin section with
new CopyWebpackPlugin({
patterns: [{
from: './client',
to: 'client'
}]
})
From here, followed the instructions on the Brightsign GitHub to setup the NodeJS presentation. Added an HTML5 widget to the presentation with the Site Source URL at http://localhost:9090.
Under Presentation Settings>Support Content>Files I added the node-server.zip file created by webpack.
And it's still not doing what I need. Looks like it's technically working but the XD1033 isn't capable of playing my content (a relatively simple 2D game) smoothly. It will show the Unity player but has a hard time loading the game assets. But, if I access the url from a laptop connected to the Brightsign it loads just fine. A simpler game or a more powerful Brightsign might work better.
I might be able to get it working better with some optimization and tweaking but at the moment it's not worth my time and effort. I can just build for Windows and use a PC. Was just trying to use a Brightsign since we've found them easier to maintain long term. Might come back to it if I get bored and will update if I get it working better.